As enterprise applications continue to increase in complexity, a commensurate increase in computational power is required to perform those applications. Because data centers continuously strive to achieve efficiencies in floor space, in power and data distribution, and in system management in the face of the ever increasing number of servers deployed, a trend has emerged toward greater densification in the manner in which those servers are physically configured. For example, servers are currently available with multiple processors in very low profile configurations that can be deployed in rack structures. One example is the Proliant®1 DL360 G4 server available from Hewlett Packard Company, which has a height of one rack unit and employs two processors. Thus a single 42 U (unit) rack can contain as many as 42 such servers. An even denser configuration can be achieved using a 1/2U Proliant® BL p-Class blade server from Hewlett Packard Company, of which up to 96 such blade servers can populate a 42 U rack. 1Proliant is a trademark of the Hewlett Packard Company.
With increased density in processing power also comes a commensurate increase in the amount and density of power dissipated by the computational components in the form of heat. One of the challenges faced by data centers deploying these densely configured servers is how to provide sufficient cooling to these densely populated racks. Without sufficient cooling, the servers and particularly their components are prone to reduced performance, shorter life and outright failure, which can lead to higher costs and even catastrophic results for the data center.
Historically, a room oriented cooling infrastructure was sufficient to handle this cooling problem. Such an infrastructure was typically made up of one or more bulk air conditioning units designed to cool the room to some average temperature. This type of cooling infrastructure evolved based on the assumption that the computer equipment is relatively homogenous and that the power density is on the order 1-2 Kilowatts per rack. The high density racks mentioned above, however, can be on the order of 20 Kilowatts per rack and above. This increase in power density, and the fact that the equipment can be quite heterogeneous leads to the creation of hotspots that can no longer be sufficiently cooled with simple room-oriented cooling systems.
This increase in local power density has led to the development of numerous localized cooling components that can be deployed more proximately to the racks containing the computational components themselves. These infrastructure components include cooling units that employ fans and heat exchangers that can be distributed locally within rows of racks to meet the specific cooling requirements of the computational components within the rows. Cooling components have also been integrated within individual rack assemblies. These newer cooling components allow data centers to build a cooling infrastructure that is locally distributed throughout the computational components, and which is tailored to the specific computational components deployed by the data center. Given the often heterogeneous nature of a data center's computational components, its overall cooling infrastructure may consist of a combination of room-oriented, row oriented and/or rack-centric cooling components.
A further trend that has emerged from the densification of computer components is that data centers have begun seeking fully assembled and tested computational system components as lieu of purchasing individual servers, assembling them into racks on site, loading the operating system software, and bringing the system up to an operational condition. They may even seek to have their own application software installed and fully tested on the system before taking delivery. Additionally, today's data centers are seeking to have the requisite cooling infrastructure provided with its purchase of computational component(s). In-row and rack-oriented cooling components developed for high density racks, such as those that employ heat exchangers using water or refrigerants, constitute a complex and bulky infrastructure that is added to the computational component to be cooled.
This cooling infrastructure, combined with an already heavy rack of computational components creates a very large, very cumbersome integrated system that presents an enormous challenge to ship to the data centers and then to install them. Data center hallways, doors and isles are simply not typically designed to facilitate their delivery and installation in this newly desired level of integration. Moreover, high-density computational components present significant challenges at the time of installation in providing power and data distribution infrastructure as well. The sheer number of connections required to these dense configurations can create enormous amounts of cabling. Finally, because today the infrastructure is delivered fully integrated with the computational components, a considerable amount of time is still required to bring the systems up after delivery. Power lines, data lines, air duct and coolant lines must all still be interfaced to the infrastructure before the systems can be brought up to an operational level.